Spark-plug



l. AND W. SHARP.

SPARK PLUG "Partnr vors JOHN SHARP ANI) fLLAl SHARP, OF CLEVELAND, OHIO.

SEABK-PLG.

Specification of Letters Patent.

Patented J an. 25,

Application filed October 2Q, i919. Serial Ne. 331,799.

T0 all zu/"wm t may concern.:

Be it known that we, JOHN Anr and ViLLIAM SHARP, citizens of the United States, andY residentsof Cleveland, in the county ot Cuyahoga and State et Ohio, have invented certain new and kuseful mprovements in Spark-Plugs, of which we hereby declare the ollowingto'be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

rlhe objects of the invention are to provide an improved form of spark plug, so constructed as to save time and labor in manufacturing and assembling the parts.

ln this device, a separate packingv and holding nut or sleeve for retaining the central insulating core is dispensed with and the central insulating core is provided with integral attaching means preferably consisting ot a coarse screw thread, each turn of which presents tapered shoulders which engage similar shoulders on the female screw in the body portion of the plug.

Each of these shoulders forms a seat that is gas proot when packing is interposed between the insulator and the said metal body.

rthis packing is also composed ot' a yielding and heat resisting` substance or compound which not only prevents conduction ot heat from the metal body to the central core but also yields to pressure and prevents the breakage of the insulating core due to the irregular expansion and contraction ot the metal body and core, and ditl'erent ratios ot expansion of the two materials.

rIhe central insulation is also provided with a hexagonal extremity permitting the use or' a wrench to adjust it in place or to renew the part.

The ground terminal lis also rigidly supported to prevent it from reducing or lengthening the spark gap.

rl`he sparking terminals are also made oif heat resisting and non magnetic metal such as nickel. or nickel alloys which prevents the attraction of iron particles worn from the cylinder, from accumulating on the spark plugs, and shortening the length of the spark gap.

The invention is illustrated in the accompanying drawings, hereinafter described and specifically pointed out in the claims.

ln the accompanying` drawings Figure l is a side elevation of the device, Fig. 2 is a central longitudinal section of the device,

Fig. 3 'is a betten view thereof, a top view theree'` Fig. 5 is a longitr 'on oi'.l the ins l uniting sheet shown in Fig. 6 is a perspective ot one ot the pz' ckwashers shown in Fig., 2, Fig. 's perspective of a wire terminal.

n these views it is the metal body oi' the ark plug provided with a central opein the upper portion of which is interi screw threaded at il.

'lVithin this opening is screwed the central insulating core D the lower end of which is screw threaded at for vertical adjustment in said metal body.

fr shoulder upon the central insulation is tightly pressed against a resilient washer G which is clamped between said shoulder and the upper surtace of said body.

The screw thread of the insulation is machined a little scant in diameter so as to leave a clear annular space between the inner and outer threads, and a sheet R of heat resisting substance similar to asbestos can be interposed between the inner and outer screw threads and will be tightly clamped between the opposed sides et the threads, thus preventing the transmission of heat Jfrom the metal to the core and also torming a packing which prevents gas escaping. T his sheet is also resilient to yield to pressure and to prevent the core from breaking when the parts irregularly expand and contact, and to protect the insulator D when it is tightly screwed into place.

The central electrode l'l is provided with a shoulder l which engages a shoulder J in the core and a yielding washer K prevents the passage of gas through the central opening L through which the electrode passes.

The ordinary clamping and lock nuts M and N for this electrode are shown and a packing washer between the central insulation and the clamping nut prevents leakage of gas.

The ground terminal P is preferably braced so that it can not revolve by means of two extremities P', P', which are inserted at spaced points in the metal body.

Having described the invention, what we claim as new and desire to secure by Letters Patent is:

l. ln a spark plug, a metal body having a central screw threaded opening7 a central insulation provided with a screw threaded extremity, adjustable in said screw threaded opening, and a sheet of resilient and heat resisting material interposed between said screw threaded portions of said metal body and central insulation.

2. In a spark plug, anietal body provided with a central screw threaded opening, a central insulation having an externally .screw threaded inner extremity adjustable in said screw threaded opening in said body, the diameter of said central insulation being less than the diameter of said opening in said metal body, providing an annular space and a packing sheet of resilient and heat resisting material interposed between said insulation and metal body, in said annular space.

3. In a spark plug, a metal body having a. screw threaded opening, a central insulation, having a corresponding screw threaded portion of less diameter than said screw threaded opening, a packing of resilient and heat resisting material inserted between the screw threaded portions of said metal body and central insulation, and said central insulation having a shoulder, and a resilient washer interposed between said shoulder and said metal body.

In testimony whereof we hereunto set our hands this 15 day of October, 1919.

JOHN SHARP. WILLIAM SHARP.

In presence of- S. W. SANGSTER, WM. M. MONROE. 

